Textile fabric with variable heat-shrunk yarn constituents

ABSTRACT

A method for forming a texture patterned fabric by selectively printing a corresponding pattern of heat absorbing fluid to the greige fabric to form zones of differential heat absorption capacity across the fabric. The differential heat absorption properties across the fabric are then used to selectively heat shrink yarns surrounding locations of fluid application.

TECHNICAL FIELD

The present invention relates to textile materials and more particularlyto textile materials with textured surface patterning formed by theselective application of heat absorbing fluid to the greige fabric priorto heat setting. Methods of formation are also provided.

BACKGROUND

Fabrics in general are well known. By way of example only, priortechniques for forming fabrics include weaving, stitch bonding, warpknitting, tricot knitting, raschel knitting and the like. In the pasttextured patterning across fabrics has been carried out by varioustechniques including shaving, impinging by hot air so as to selectivelymelt surface yarns in a desired pattern, chemical degradation in adesired pattern using acid etching or the like, and impingement by highpressure water streams so as to dislodge and/or reorient surface fibersin a desired pattern. While such techniques have been useful, they havenonetheless been relatively complex and difficult to carry out due tothe need to use specialized equipment to carry out the patterningprocedures. Moreover, these techniques result in abrasion and/orreorientation of surface yarns thereby changing the constructionfeatures across the fabric

SUMMARY

The present invention provides advantages and alternatives over theprior art by providing a method for forming a patterned textile fabricby applying a pattern of heat absorbing fluid to a greige fabric surfaceusing, for example, printing equipment to form zones of differentialheat absorption across the fabric. The differential heat absorptionproperties across the fabric are then used to selectively heat shrink atleast a portion of the yarns in locations outboard of the fluidapplication. Because the pattern is formed by printing or otherapplication equipment, the resultant pattern may be of substantialcomplexity. The resulting fabrics may find uses in any number ofapplications including residential and/or automotive upholstery whereinsubstantial fabric integrity is required.

According to one aspect, yarns with different heat shrinkage charactermay be used in combination with one another across the fabric structure.It is also contemplated that single surface yarn system may be used ifdesired.

According to another aspect, differential pile heights across the fabricmay substantially correspond to differential dye acceptancecharacteristics thereby providing synergistic tactile and visualdifferentiation across the fabrics.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which are incorporated in and which constitutea part of this specification illustrate several exemplary constructionsand procedures in accordance with the present invention and, togetherwith the general description given above and the detailed descriptionset forth below, serve to explain the principles of the inventionwherein:

FIG. 1 illustrates schematically a stitch bonding process forselectively forming a patterned surface yarn system and a cooperatingground yarn system through a fibrous substrate;

FIG. 2 illustrates schematically the stitching of a ground yarn in anarrangement of substantially flat chain stitches by a multiplicity ofreciprocating needles;

FIG. 3 illustrates schematically the stitching of a surface yarns in apattern of loops by a first pair of cooperating reciprocating needles;

FIG. 4 illustrates schematically a treatment process for selectivelyheat shrinking surface yarns across a fabric;

FIG. 5 further illustrates schematically an exemplary process whereby aheat sink fluid pattern is applied to the face of the fabric by a rotaryscreen printer, resulting in a pattern of treated and untreated areas onthe fabric surface;

FIG. 6 illustrates schematically a cross-section taken through thefabric with zones treated with heat absorbing fluid; and

FIG. 6A illustrates schematically the fabric of FIG. 6 subsequent toheat treatment.

While a description will hereinafter be provided in connection withcertain exemplary embodiments, procedures and practices, it is to beunderstood and appreciated that in no event is the invention to belimited to the embodiments, procedures and practices as may beillustrated and described herein. On the contrary, it is intended thatthe present invention shall extend to all alternatives and modificationsas may embrace the broad principles of this invention within the truespirit and scope thereof.

DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made to the drawings, wherein to the extentpossible like reference numerals are utilized to designate like elementsthroughout the various views. A method as utilized to form a fabric ofstitch bonded construction is illustrated schematically in FIG. 1. Theillustrated method utilizes a stitch bonding machine 10 as will be knownto those of skill in the art. Importantly, it is to be understood andappreciated that while various contemplated practices will hereinafterbe described in relation to pile fabrics formed on a stitch bondingmachine, the invention is not limited to such stitch bonded pilefabrics. To the contrary, it is contemplated and intended that thetechniques of the invention are equally applicable to flat fabricsformed by stitch bonding, weaving, knitting and other techniques as wellas to pile fabrics formed by techniques other than stitch bondingincluding tufting, knitting and the like.

In the illustrated exemplary practice a substrate material 30 such as acarded and cross-lapped fleece or a needle-punched or spun bonded fleeceis conveyed to a stitch-forming position in the direction indicated bythe arrow. In a potentially preferred practice, the substrate material30 is needle-punched fleece formed from about 4 denier polyester staplefilaments although other suitable substrate materials may likewise beutilized if desired. The substrate material 30 may include a percentageof low melting point fibers such as low melting point polyester orbicomponent polyester having a core of relatively high melting pointmaterial and a sheath of lower melting point polyester to facilitateheat activated point bonding so as to enhance structural integrity.

As illustrated through simultaneous reference to FIGS. 1, 2, and 3, thestitch forming position is defined by a row of reciprocating needles 34,34′, and 34″ etc. extending in adjacent relation to one another acrossthe width of the substrate material 30 substantially transverse to thedirection of movement of the substrate material 30. As will beappreciated, while only three needles have been illustrated, in actualpractice a large number of such needles are arranged in close relationto one another in the cross machine direction between the fingers 47 ofa sinker bar.

According to the illustrated practice, three yarn systems are used toform stitches through the substrate material 30. In the illustratedpractice, a ground yarn 36 (FIG. 2) is carried through a first set ofmoveable yarn guides 38 carried by a back guide bar (not shown) forcooperative substantially fully threaded engagement with the needles 34,34′, 34″ etc. across the width of the substrate material 30. For ease ofreference, the substrate material is not illustrated in FIG. 2.

As will be appreciated by those of skill in the art, in operation theground yarn 36 is moved into engagement with the needles which, in turn,carry the ground yarn 36 in reciprocating manner through the substratematerial 30 without engaging finger elements 47 of the sinker bar so asto form an arrangement of cooperating ground yarn stitches 40 extendingin relatively closely spaced parallel rows along the substrate material30. By way of example only, and not limitation, the cooperating groundyarn stitches 40 may be held in a full chain stitch configurationalthough other stitch arrangements including tricot stitches and thelike may likewise be utilized if desired. Preferably, the spacing of thestitch lines formed by the ground yarn 36 will be close enough that theground yarn stitches 40 define a substantially continuous coveringacross the user contact surface 41 of the substrate material 30. Theground yarn 36 and the substrate material 30 thus define a substantiallystable stitch bonded structure. By way of example only and notlimitation, one ground yarn 36 that may be particularly suitable is a 70denier polyester filament yarn, although other yarns may likewise beutilized if desired.

According to one exemplary practice, a first collection of loop elements42, is formed projecting away from and standing above the ground yarnstitches across the fabric defining a user contact surface 41. Ifdesired, at least a second collection of loop elements 43, may also beformed projecting away from and standing above the ground yarn stitchesacross the fabric. In the event that multiple collections of loopelements are utilized, it is contemplated that the loop elements 42 and43 may be formed from either the same or different yarn materials. Thus,the yarns forming the pile may be characterized by either the same ordifferent heat shrinkage characteristics. In this regard, it iscontemplated that using yarns with different heat shrinkage characteracross the fabric may be desirable in some instances.

According to a contemplated practice, the loop elements 42, 43 may beformed substantially concurrently with the formation of the ground yarnstitches 40 through the substrate material 30. The loop elements 42, 43may be selectively formed in a predefined pattern across the surface 41of the fabric. In this regard it is to be understood that the firstcollection of loop elements 42 may be formed in either the same patternor a different pattern than the second collection of loop elements 43.According to a preferred practice, the loop elements 42, 43 are formedso as to cover substantially the entire face of the fabric. However, itis also contemplated that the loop elements may be present only acrossselected portions of the fabric if desired to provide a combination oftwo dimensional and three dimensional surface character.

An exemplary technique for forming the loop elements 42, 43 isillustrated in FIG. 3 wherein the substrate material 30 and ground yarn36 have been eliminated for ease of reference. According to thispractice, the first collection of loop elements 42 may be formed by asurface yarn 44 fully threaded through moveable yarn guides 46 carriedby a middle guide bar (not shown). While only a single surface yarn 44is illustrated for explanatory purposes, it is to be understood that inactual practice, multiple surface yarns 44 are used across the width ofthe fabric. During the pile formation process, the surface yarn 44 iscarried in alternating fashion back and forth between a first pair ofneedles 34, 34′ thereby forming a row of loop elements 42 as the pileyarn 44 is carried over the sinker finger 47 between the needles 34, 34′during stitch formation.

According to the illustrated practice, the second collection of loopelements 43 may be formed by a surface yarn 48 fully threaded throughmoveable yarn guides 49 carried by a front guide bar (not shown). Whileonly a single surface yarn 48 is illustrated for explanatory purposes,it is to be understood that in actual practice, multiple surface yarns48 are used across the width of the fabric. During the pile formationprocess, the surface yarn 48 is carried in alternating fashion back andforth between a first pair of needles 34, 34′ thereby forming a row ofloop elements 43.

As will be appreciated, the formation practice illustrated results inthe formation of double loops formed from two different surface yarns44, 48. As long as the surface yarns pass between the needles 34, 34′ ina regular stitch forming procedure, a substantially continuousarrangement of loop elements 42, 43 will be formed along the length ofthe technical face 41 of the fabric. Of course, a single yarn system mayalso be utilized wherein one of the surface yarns 44, 48 is eliminated.According to a potentially preferred practice, the loop elements 42, 43are formed so as to form a loop length in the range of about 1 mm toabout 5 mm and more preferably a loop length of about 3 mm. Of course,it is likewise contemplated that the fabric formed may have asubstantially flat construction. Such a construction may be achieved bysimply disengaging the sinker fingers 47. It is also contemplated thatthe fabric may be formed to have flat zones and pile-forming zones. Thestitch density for the surface yarns in the machine direction of boththe loop elements and the ground yarns is preferably about 18 to about60 stitches per inch and more preferably about 40 stitches per inch.

According to one contemplated practice wherein yarns with different heatshrinkage characteristics are utilized across the fabric surface, thesurface yarn 44 may have a high heat shrinkage capacity with shrinkageactivated at temperatures such as the fabric would encounter duringnormal heat setting operations, while the surface yarn 48 is preferablycharacterized by a substantially lower heat shrinkage capacity at thesame temperature. Accordingly, loop elements 42 shrink to a greaterextent than loop elements 43 when exposed to temperatures such as thefabric would encounter during normal heat setting. In this regard it isto be understood that the term “heat shrinkage capacity” is intended torefer to percentage of shrinkage on a length basis that a yarn undergoeswhen it is raised to a given temperature.

In the event that different yarn systems having differential heatshrinkage capacity are used, one potentially preferred high shrink yarnis a partially-oriented yarn (POY) of polyester. The polyester POY ispreferably a cold drawn yarn with a draw ratio of about 1.35 to about1.75 (most preferably about 1.57). In this regard, it is to beunderstood that the term “cold drawn” refers to yarn formed fromfilaments that are drawn at temperatures below the softening point ofthe fiber polymer. Most preferably, such drawing is carried out atsubstantially ambient temperatures. In the absence of elevatedtemperatures, substantially no thermal setting takes place during thedrawing process. The term “partially-oriented yarn” refers to filamentyarn that is drawn to a degree such that only partial longitudinalmolecular orientation is achieved. One exemplary high shrink capacitysurface yarn 44 is 72-filament bright trilobal polyester that has beencold drawn down to 150 denier. An exemplary low shrink capacity surfaceyarn 48 is a nylon yarn such as a textured yarn formed from Nylon 6 orNylon 6,6. By way of example only, one such nylon yarn is a 70 denierfalse twist textured yarn formed from Nylon 6,6. Such yarns undergo asubstantially reduced shrinkage at temperatures such as the fabric wouldencounter during normal heatsetting. As will be described furtherhereinafter, such yarn combinations facilitate the development of ahighly textured face as the greige fabric is passed through a tenter orother heating unit following formation. It is also contemplated thatother low shrink capacity yarns such as cellulosic filament yarns ofviscose rayon and the like may also be used if desired

In the event that a single yarn system is to be utilized, the selectionof the yarn material utilized will be dependent upon the degree ofdifferential height desired across the fabric. Thus, if substantialdifferential height is desired, a material with high heat shrinkagecapacity such as the polyester POY previously described may bedesirable. Likewise, if a subtle differential pile height is desiredacross the fabric, a yarn material such as the false twist nylon or thelike may be desirable.

As previously noted, it is to be understood that the stitch bondedfabric constructions as outlined above are exemplary only. In thisregard it is likewise contemplated that other greige state fabricconstructions as will be known to those of skill in the art may likewisebe utilized. By way of example only, and not limitation, suchalternative fabric constructions may include woven fabrics, warp knittedfabrics, raschel knitted fabrics, chenille fabrics and the like.

Regardless of whether a single yarn system or a multiple yarn system isutilized, the present system permits the controlled development ofsurface texturing such that different zones across the finished fabrichave different pile heights and dye acceptance characteristics therebyproviding substantial tactile and visual differentiation across thefabrics. One exemplary practice for carrying out this method is depictedschematically in FIGS. 4 and 5. As shown, after formation the greigefabric is advanced towards a printing station 20. According to anexemplary embodiment, the printing station 20 may include a rotaryscreen printer incorporating a roller 51 adapted to selectively transfera volume of heat absorbing fluid to the pile surface 41 of the greigefabric as the fabric is advanced through printing station 20. The screenprinting roller may include a screen pattern 60 disposed about itscircumferential face 52. The screen pattern 60 is selected according tothe pattern desired to be imparted on the fabric, and may be easilyaltered or substituted as desired. Due to the versatility inherent inscreen printing, any number of patterns may be imparted to the fabric,ranging from simple geometric forms to such complex patterns ascurvilinear forms and text. It is also contemplated that other printingsystems may be used to apply the pattern of fluid to the fabric. By wayof example only, and not limitation, various alternative fluid printingtechniques as may be utilized include flat bed screen printing, fluidjet printing and the like that are suitable for the application ofcomplex patterns. Regardless of the printing technique utilized, theheat absorbing fluid is transferred to the fabric such that a desiredpattern of wet or treated zones 62 and dry or untreated zones 64 isproduced (FIG. 6).

In the event that the surface 41 incorporates POY polyester yarns asdescribed above (either alone or in combination with a higher heatshrinkage yarn), the heat absorbing fluid applied to the greige fabricmay have a relatively low heat capacity such as a solution of water withan appropriate thickener such as polyacrylate or the like sufficient toincrease the solution's viscosity as may be desired to promote theprinting process. A viscosity of about 12,000 centipoise may bedesirable to promote controlled application and retention of the heatabsorbing fluid in patterned relation across the greige fabric. However,higher and lower viscosity levels may be used as desired. Of course, itis contemplated that other aqueous or non-aqueous solutions may likewisebe utilized if desired.

According to one contemplated practice, the heat absorbing fluid may bechilled prior to application to the fabric. By way of example, it hasbeen found that chilling an aqueous polyacrylate solution to about 40degrees Fahrenheit prior to application to the fabric may be desirable.As will be described more fully hereinafter, the applied fluid ischaracterized by a heat capacity so as to substantially protect thewetted portions of the fabric from experiencing temperatures that wouldcause yarn shrinkage. If desired, the applied solution may furtherinclude a fugitive tint. The fugitive tint is a temporary coloring thatallows an operator to verify that the fabric has been properly wettedaccording to the desired pattern, thus providing a quality control meansto detect and correct any printing errors prior to further processing.Additional or alternative additives may be added to the solution asdesired.

As depicted in FIG. 4, after the heat absorbing fluid is applied to thesurface 41 of the fabric, the fabric is advanced through a heating unit52 such as a tenter frame for application of heat. Of course, otherheating units may likewise be used including laser heaters and the likeas may be known to those of skill in the art. As the fabric is advancedthrough the heating unit 52, the fabric is exposed to heat, which tendsto preferentially shrink the high shrink capacity face yarns formingloop elements 42 such as the POY polyester in the dry portions of thefabric as depicted schematically in FIG. 6A. In the dry portions of thefabric the low shrink capacity yarns forming the loop elements 43 shrinkmuch less than the high shrink capacity yarns in those regions. In thewet zones both the high shrink capacity surface yarns and the low shrinkcapacity yarns experience relatively little if any shrinkage. By way ofexample only, according to one potentially preferred practice, thefabric is advanced through about 30 feet of a tenter frame at a rate ofabout 50-60 yards per minute with a temperature setting of about 200° F.At these settings, it has been discovered that in a stitch bonded fabricmade up of a 4 denier needled fleece (substrate 30) including 3 mm loopsof 70 denier nylon in combination with 3 mm loops of trilobal POYpolyester cold drawn to 150 denier, the dry loops of POY polyester willshrink to about 50% of their original length while the wetted loopsexhibit substantially no shrinkage.

Referring again to FIG. 4, after the fabric is passed through theheating unit 52, it is preferably wound onto a beam 54 with substantialtension. In this regard it has been found that winding the fabric athigh tension levels tends to stabilize the fabric and lock in the heatinduced texturing. The fabric may thereafter be subjected to hot waterheat setting followed by a dyeing process such as jet dyeing or beamdyeing as may be desired. After dyeing, the fabric is dried, in a dryingunit such as a tenter frame or the like. It has been found that thedifferential shrinkage imparted in the initial heating step issubstantially retained. The fabric may thereafter be subjected to abrushing or sanding operation to shear the high and/or low loops acrossthe surface.

The result of the process as described above is a fabric having a threedimensional pattern defined by areas with differential pile height.Without being limited to a specific theory, it is believed that theselective wetting of the fabric protects the wetted zones while thecharacter of the pile yarns concurrently facilitates shrinkage of thedry zones at relatively low levels of heat input during initial heating.Thus, selective shrinkage can be achieved without overwhelming theprotective heat absorbing fluid.

As previously noted, it has been found that the differential pileheights may substantially correspond to differential dye acceptancecharacteristics across the fabric. That is, when the fabric is subjectedto substantially uniform dyeing, the zones subjected to protectivewetting take on a substantially different shade relative to the zoneswhere substantial shrinkage has taken place. Thus, there is acomplementary tactile and visual differentiation between the treated anduntreated zones across the fabric.

Aside from the ability to provide simultaneous differentiation of bothpile height and dye acceptance character, the process of the instantinvention is believed to provide the benefit of substantially retainingthe integrity of the fabric construction. Specifically, by using heatinduced shrinkage rather than yarn removal or displacement, it isbelieved that the structural character of the fabric system may besubstantially retained. This, in turn, may promote strength in the finalproduct.

It is to be understood that while the present invention has beenillustrated and described in relation to potentially preferredembodiments, constructions, and procedures, that such embodiments,constructions, and procedures are illustrative only and that theinvention is in no event to be limited thereto. Rather, it iscontemplated that modifications and variations embodying the principlesof the invention will no doubt occur to those of ordinary skill in theart. It is therefore contemplated and intended that the presentinvention shall extend to all such modifications and variations as mayincorporate the broad aspects of the invention within the true spiritand scope thereof.

1. A method of forming a fabric characterized by localized variablesurface texturing and substantially aligned dye shading, the methodcomprising: providing a fabric comprising a plurality of pile-formingyarn elements formed from a partially oriented polyester yarncharacterized by a predefined heat shrinkage capacity; printing a volumeof heat absorbing fluid onto the fabric according to a predeterminedpattern to define treated zones where the fluid is applied and untreatedzones where the fluid is not applied; heating the fabric such thatpile-forming yarn elements of partially oriented polyester yarn whichare located in untreated zones undergo preferential shrinkage relativeto pile-forming yarn elements of partially oriented polyester yarnlocated in treated zones; and subjecting the fabric to a substantiallyuniform dye treatment, wherein pile-forming yarn elements of partiallyoriented polyester yarn which are located in untreated zones arecharacterized by differential dye acceptance relative to pile-formingyarn elements of partially oriented polyester yarn located in treatedzones such that the fabric exhibits differential color shading acrossthe surface corresponding substantially to the pattern of fluid appliedduring the printing step.
 2. The invention of claim 1, wherein thefabric is a stitch bonded fabric.
 3. The invention of claim 1, whereinthe printing is carried out by a rotary screen printer.
 4. The inventionas recited in claim 1, wherein the heat absorbing fluid comprises anaqueous polyacrylate solution.
 5. The invention as recited in claim 4,wherein the polyacrylate solution is chilled below room temperature forapplication during the printing step.
 6. The invention as recited inclaim 1, comprising the further step of tip shearing substantially allpile-forming yarn elements in the treated and untreated zones.
 7. Afabric formed by the method of claim
 1. 8. A method of forming a fabriccharacterized by localized variable surface texturing, the methodcomprising: providing a fabric comprising a first plurality ofpile-forming yarn elements formed from a first yarn characterized by afirst heat shrinkage capacity and a second plurality of pile-formingyarn elements formed from second yarn characterized by a second heatshrinkage capacity, wherein the first heat shrinkage capacity is greaterthan the second heat shrinkage capacity; printing a volume of heatabsorbing fluid onto the fabric according to a predetermined pattern todefine treated zones where the fluid is applied and untreated zoneswhere the fluid is not applied, wherein at least a portion of thetreated zones and at least a portion of the untreated zones includepile-forming yarn elements formed from the first yarn in combinationwith pile-forming yarn elements formed from the second yarn; and heatingthe fabric such that pile-forming yarn elements formed from the firstyarn and which are located in untreated zones undergo preferentialshrinkage relative to pile-forming yarn elements formed from the firstyarn which are located in treated zones and relative to pile-formingyarn elements formed from the second yarn in both treated and untreatedzones.
 9. The invention of claim 8, wherein the fabric is a stitchbonded fabric.
 10. The invention of claim 8, wherein the printing iscarried out by a rotary screen printer.
 11. The invention of claim 8,wherein the first yarn is a multi-filament partially oriented polyesteryarn.
 12. The invention as recited in claim 11, wherein the second yarnis nylon.
 13. The invention as recited in claim 11, wherein the secondyarn is a cellulosic yarn.
 14. The invention as recited in claim 8,wherein the heat absorbing fluid comprises an aqueous polyacrylatesolution.
 15. The invention as recited in claim 14, wherein thepolyacrylate solution is chilled below room temperature for applicationduring the printing step.
 16. The invention as recited in claim 8,comprising the further step of tip shearing substantially allpile-forming yarn elements in the treated and untreated zones.
 17. Afabric formed by the process of claim
 8. 18. A method of forming afabric characterized by localized variable surface texturing andsubstantially aligned dye shading, the method comprising: providing afabric comprising a first plurality of pile-forming yarn elements formedfrom partially oriented polyester yarn characterized by a predefinedfirst heat shrinkage capacity and a second plurality of pile-formingyarn elements formed from at least one of the group consisting of nylonand cellulosic yarn characterized by a second heat shrinkage capacity,wherein the first heat shrinkage capacity is greater than the secondheat shrinkage capacity; printing a volume of heat absorbing fluid ontothe fabric to define treated zones where the fluid is applied anduntreated zones where the fluid is not applied, wherein at least aportion of the treated zones and at least a portion of the untreatedzones include pile-forming yarn elements formed from the first pluralityof pile-forming yarn elements in combination with pile-forming yarnelements formed from the second plurality of pile-forming yarn elements;heating the fabric such that pile-forming yarn elements formed from thepolyester yarn and which are located in untreated zones undergopreferential shrinkage relative to pile-forming yarn elements formedfrom the polyester yarns which are located in treated zones and relativeto the second plurality of pile-forming yarn elements in both treatedand untreated zones; and subjecting the fabric to a substantiallyuniform dye treatment, wherein pile-forming yarn elements of partiallyoriented polyester yarn which are located in untreated zones arecharacterized by differential dye acceptance relative to pile-formingyarn elements of partially oriented polyester yarn located in treatedzones such that the fabric exhibits differential color shading acrossthe surface corresponding substantially to the pattern of fluid appliedduring the printing step.
 19. A fabric formed by the process of claim18.